/**
 * Software License, Version 1.0
 * 
 * Copyright 2003 The Trustees of Indiana University.  All rights reserved.
 * 
 *
 *Redistribution and use in source and binary forms, with or without 
 *modification, are permitted provided that the following conditions are met:
 *
 *1) All redistributions of source code must retain the above copyright notice,
 * the list of authors in the original source code, this list of conditions and
 * the disclaimer listed in this license;
 *2) All redistributions in binary form must reproduce the above copyright 
 * notice, this list of conditions and the disclaimer listed in this license in
 * the documentation and/or other materials provided with the distribution;
 *3) Any documentation included with all redistributions must include the 
 * following acknowledgement:
 *
 *"This product includes software developed by the Community Grids Lab. For 
 * further information contact the Community Grids Lab at 
 * http://communitygrids.iu.edu/."
 *
 * Alternatively, this acknowledgement may appear in the software itself, and 
 * wherever such third-party acknowledgments normally appear.
 * 
 *4) The name Indiana University or Community Grids Lab or NaradaBrokering, 
 * shall not be used to endorse or promote products derived from this software 
 * without prior written permission from Indiana University.  For written 
 * permission, please contact the Advanced Research and Technology Institute 
 * ("ARTI") at 351 West 10th Street, Indianapolis, Indiana 46202.
 *5) Products derived from this software may not be called NaradaBrokering, 
 * nor may Indiana University or Community Grids Lab or NaradaBrokering appear
 * in their name, without prior written permission of ARTI.
 * 
 *
 * Indiana University provides no reassurances that the source code provided 
 * does not infringe the patent or any other intellectual property rights of 
 * any other entity.  Indiana University disclaims any liability to any 
 * recipient for claims brought by any other entity based on infringement of 
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 *
 *LICENSEE UNDERSTANDS THAT SOFTWARE IS PROVIDED "AS IS" FOR WHICH NO 
 *WARRANTIES AS TO CAPABILITIES OR ACCURACY ARE MADE. INDIANA UNIVERSITY GIVES
 *NO WARRANTIES AND MAKES NO REPRESENTATION THAT SOFTWARE IS FREE OF 
 *INFRINGEMENT OF THIRD PARTY PATENT, COPYRIGHT, OR OTHER PROPRIETARY RIGHTS. 
 *INDIANA UNIVERSITY MAKES NO WARRANTIES THAT SOFTWARE IS FREE FROM "BUGS", 
 *"VIRUSES", "TROJAN HORSES", "TRAP DOORS", "WORMS", OR OTHER HARMFUL CODE.  
 *LICENSEE ASSUMES THE ENTIRE RISK AS TO THE PERFORMANCE OF SOFTWARE AND/OR 
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 */
package cgl.narada.matching.tagvalue;


/**
   This keeps track of the destinations, and the number of predicates within 
   each destination that are interested in a particular edge. This 
   irrespective of wether the edge in question is connected to another node 
   in the matching tree graph or if its simply a destination edge. The 
   destinations thus returned need to be fed into the event routing protocol, 
   which provides the shortest routes to reach destinations at different 
   levels.
   
   @author Shrideep Pallickara
   $Date$
   $Revision$
*/

public class EdgeAttributes implements MatchingDebugFlags {
  /** Contains a list of destinations interested in the event. */ 
  private int interestedDestinations;
  
  /** For each destination, contains the number of predicates within that 
      destination that are interested in the event */
  private int[] predicatesInterested; 
  public EdgeAttributes() {
    predicatesInterested = new int[32];
  }

  /** This method increments the predicate count associated with the edge.
      When subcriptions are being added - newly created or existing - edges
      need to be update with reference counts for predicates within each
      destination. This plays a major role in determing when a destination
      need no longer be served.
  */  
  public void incrementPredicateCountForDestination(int _destination) {
    interestedDestinations = interestedDestinations | _destination;
    int destinationID = 0;

    for (int i =1; i < 32; i++) {
      if ( (_destination &1) == 1) {
	destinationID = i;
	break;
      }
      _destination >>= 1;
    }
    
    predicatesInterested[destinationID-1]++;
    if (EdgeAttributes_Debug) {
      System.out.println("For  destination " + destinationID + 
			 " num of predicates interested = " +   
			 predicatesInterested[destinationID-1]);
    }
  }
  
  /** This method provides for decrementing the reference count assocaited 
      with messages. When the reference count associated with a given
      destination is reduced to zero, we say that the destination is no longer
      interested in the edge, and proceed to remove it from the list of 
      destinations associated with the edge */
  public void decrementPredicateCountForDestination(int _destination) {
    int tempVar = _destination;
    int destinationID = 0;
    for (int i =1; i < 32; i++) {
      if ( (_destination &1) == 1) {
	destinationID = i;
	break;
      }
      _destination >>= 1;
    }
    predicatesInterested[destinationID-1]--;
    
    if (EdgeAttributes_Debug) {
      System.out.print("Interested Destinations: Before="+ 
		       interestedDestinations);
    }
    
    if (predicatesInterested[destinationID-1] == 0) {
      /** Since the number of predicates interested in this edge for the 
	  specific _destination is zero, we have to remove the destination
	  indicator from the interestedDestination indicator */
      interestedDestinations = 
	interestedDestinations & performNotOperation(tempVar);
    }
    System.out.println(" After "+ interestedDestinations);
  }
  
  /** This method serves as the precursor to the deletion of certain
      nodes and edges, in response to the removal of an interest in 
      subscription predicates. */
  public boolean containsDestinations() {
    if (interestedDestinations != 0) 
      return  true;
    else return false;
  }

  /** This performs an inversion of the bits in an integer. There are no
      unary operators which do this in Java. I have implemented the NOT
      operation using an XOR operator */
  private int  performNotOperation(int value) {
    int newVal = value ^ 0xFFFFFFFF;
    return newVal;
  }

  /** Returns the list of destinations associated with the edge */
  public int getDestinations() {
    return interestedDestinations;
  }
  
  /** Returns the predicate count associated with the destinations 
      @return The predicate count associated with individual destinations.
   */
  public int[] getPredicateCountForDestinations() {
    return predicatesInterested;
  }


  public static void main(String[] args) {
    EdgeAttributes attrib = new EdgeAttributes();
    attrib.incrementPredicateCountForDestination(8);
    
  }
}
